Personally, I think you are all planning it all wrong using FP's to begin with.
Firstly, on the very rare occasion I use FP's, I always come back at the alloted time. I make sure I don't stray too far from it. For example, yesterday, I went to DAK, got a FP for Kilimanjaro Safari. There were signs there saying clearly to return within the time window. I was surprised, 'cause it never occurred to me people had to be told <.< So while I had about an hour, I went to the Pangani Forest Trail, and enjoyed reading, and taking pictures, and asking CMs questions about the animals.
I got back at 11.20am, my FP was for 11.30am. I sat on a bench right next to it and waited. I noticed a couple people had arrived early and were not allowed in. I figured that's normal, it never occurred to me as I said that CMs never enforced time frames for being early or late. At 11.30, I went up and she looked at the time, and let me through. The second CM merely took the ticket and never checked.
Now like I said, I rarely ever take FPs, and when I do, I actually end up giving them away. And in all honesty, the only time I take FPs, it is when I hit DAK or Epcot. DHS, I wait for Fantasmic to happen. The Park clears out and I end up doing ToT and RnRC at that time. The best part is MK. I always go to the park around 8pm. Depending on when Wishes plays, it'll depend on when I do the rides. I have noticed the best time to go to MK is after Wishes. I get at least 6 to 8 rides done in a couple hours once Wishes has gone by. The park clears out so quickly that there are hardly any lines.
But back to the original posting about FPs, I do believe it is the right thing to enforce the time frame. I mean what was the point of having the time frame to begin with if it was never respected. Like I said it never occurred to me that people would actually deliberately come later in the day when their FPs are 5 hours past due time. In a way I'm glad it's enforced. Cause I make the effort to be on time, so should others <.<